Lighting fixtures are an important part of any home, commercial or industrial setting. Without adequate light from such fixtures, people could not work or live as conveniently as we do today.
However, some environments are hostile to conventional lighting fixtures. One example is any area where water impinges on the lighting fixture. In such cases, water may impinge on the lighting fixture because of wind blown rain or some sort of industrial or commercial process that requires the use of a high pressure water spray.
In general, the risk inherent in such cases relates to the fact that electricity and water are incompatible. Where water penetrates a lighting fixture the moisture may cause a fire. Alternatively, incident moisture may corrode the fixture, rendering it inoperative.
The protection of enclosures against the ingress of dirt or against the ingress of water is defined in IEC529 (BSEN60529:1991), promulgated by the International Electrotechnical Commission. The degrees of protection are commonly expressed as “IP” followed by two numbers, e.g. IP65, where the numbers define the degree of protection. The first digit (Foreign Bodies Protection) shows the extent to which the equipment is protected against particles, or to which persons are protected from enclosed hazards. The second digit (Water Protection) indicates the extent of protection against water. In this example, for a rating of “IP 65,” the first digit “6” indicates that the enclosure is dustproof, and the second digit “5” indicates that the enclosure protects against high-pressure jets from all directions. IP65 is the rating required for satisfactory protection in car washing facilities and similar environments.
Prior efforts to exclude water from lighting fixtures have primarily been limited to incandescent or compact fluorescent light (CFL) fixtures. This has proved to be the most practical because of the compact nature of such devices and because the compact nature of such devices makes it easy to construct a globe that may be used to easily cover such devices. In these cases, the globe may be provided with a set of threads that engages a socket disposed around the incandescent or CFL socket.
However, many applications require the use of fixtures that accept 2-foot, 4-foot and 8-foot long fluorescence bulbs. This is the case because of the need for high levels of illumination at a work surface, because of a high ceiling or because of the need to achieve a uniform illumination level at the work surface. However, in the past, it has not been possible to produce a fixture that accepts such light sources because it was not possible to seal such fixtures against moisture. Accordingly, a need exists for better ways of constructing such fixtures.